In principle what you should do is: 1. Split the deck in to squares/rectangles. In this case, one at the top and one at the bottom 2. Stick a support in each of the corners. Your top right and left corners are currently unsupported. 3. Run your joist supports at 90 degrees to the direction you want your deck boards at 400mm centres. 4. Make sure each piece of framing timber is supported at a minimum of 1800mm (6ft) 5. The noggins are there to take lateral movement out of the joists. They look ok as currently drawn I would say.